Meiji makes nice stuff. One thing I would be sure to check is the fine focus travel. I have a Meiji ML2000 microscope and on that piece the fine focus, (although it is coaxial with the coarse focus) only provides a travel of a couple millimeters or so, and then you need to "back it off". Don't know if that's the case with this block or not._________________http://www.krebsmicro.com

Following on Charles' comments above.
This is the focus block adjustment dials on a Swift compound scope, bought very cheaply on e bay. Sold for parts and had a decent stand with a mechanical stage for x-y movement. Coarse (large dial) with fine adjustment dial in center. I believe this a M100 scope.
Anyway, both coarse and fine adjustments move the stage the full 25mm. Large dial is 50mm diam.
Seems suitable for macro photo stacking. Posted here as the fine adjustment on some scopes have very limited travel (1-2mm or less) and are unsuitable for our purposes.
_________________NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

And the small dial has 6 tick marks!
Large dial: 4 full rotations moves stage 25mm.

Takes the small dial 36 rotations to move stage 25mm. 1 rotation=0.7mm.
But as the small dial moves, the large dial moves with it but at a slower rotational speed.

Not bad for $26.45. It came on a microscope stand complete with mechanical stage, substage condensor and built-in light. Just need a binocular top, eyepieces and objectives and I have a decent scope. There are some fantastic bargains on e bay._________________NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

For stacking, the fine focus is not much different from a Proxxon milling table. Full turn = 1.0 mm for the table, 0.7 mm for the scope.
--Rik

But for practical operation a lot different.

The Proxxon table is a nice and accurate piece of equipment with movement in 2 axes, forward/backward and right/left. To use it you still have to another piece to move the camera or specimen in the third axis (up/down).

I'm getting more and more convinced that a microscope stand is the way to go. They are designed to move objects accurately in very small steps. Heck, with a 100x oil immersion lens and 10x eyepieces they control the movement of a specimen that is magnified 1000x.

The dial on the Proxxon is 34mm diam. which moves a "measuring" dial of only 20mm diam. There are 20 tick marks. The distance between tick marks is 3mm and this moves the table 0.05mm. With great care one can actually move the table 0.01mm, but 0.025mm is more likely the smallest increment.

Compare this with the Swift M100 stand. It allows for movement in all 3 axes. The fine adjustment dial is 33mm diameter and it moves around a scale that is 34.5mm inside diam that has 240 tick marks. The fine adjustment dial has 6 tick marks, 17mm between each. This 17mm covers 40 of the smallest tick marks on the coarse adjustment dial. These 40 tick marks represent a forward movement of 0.117mm. Thus moving the fine adjustment dial just 1 tick mark will result in a forward movement of 0.003mm. I doubt that this is practical but it should be easy to move the fine adjustment in 5 division increments = 0.015mm.

_________________NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

I'm not debating whether a good microscope stage is better than a milling table -- clearly it is.

What I'm trying to tease out is exactly why and how the stage is better, so that I'll know what to look for and how to distinguish a good stage from the others. In addition to all those good buys on eBay, there are also a lot of clunkers with hardened grease, limited travel, unmarked dials, and fine focus ratios that are really pretty coarse.

In the current case, Proxxon table versus Swift M100 stand, I had not noticed the difference in size & character of the marked dials. Obviously there is a big difference in readability between the two units.

I'm still not sure I understand the difference in usable movement, though.

In my experience, the ultimate limit has always been how small a movement I can make. If an indicator is coarsely marked or too small to read, I can add a finer scale or look through a magnifying glass. But if the mechanism sticks when I try to turn the adjusting knob, then moves too far when it comes unstuck, that's much harder to deal with. My current setup uses a milling table with a fairly coarse thread, 1 turn = 2.54 mm. It's carefully adjusted and lubricated, but even so, the finest movement I can make is limited to about 0.005 mm by stick/release and the compliance of my skin.

With this in mind, I was sort of expecting to hear that the stage is better because it's silky smooth, while the table is just a little bit sticky. When you say that 0.025 mm is more likely the smallest increment with the table, is stickiness what you're referring to? Or is it really a matter of reading the indicator, as suggested by the numbers that you've used?

I have a similar question about the stage. You mention that it's maybe not practical to move the fine adjustment by 1 tick mark. Why is this?

Rik:
Perhaps I've been lucky but so far everything I have bought has been accurately described by the seller; especially honest with regard to any shortcomings/problems.

I have moved the Proxxon wheel such that the resulting forward movement is 0.01mm but it took a magnifying glass and a lot of tension on my mind (big hands, big fingers, ageing eyesight). So much easier for me to work it for 0.025mm or greater increments.

I just tried moving the fine adjustment on the Swift; it's silky smooth. I can easily rotate it just 1 tick mark (for a forward movement of 0.003mm) without a magnifyng glass. But at the moment I can't think of why I would want to make a stack of 0.003mm frames.

I also recently bought an old Parco scope (appears to be a re-labelled Meiji TM490). This is the scope that came with the 4x/0.1 objective
HERE
plus 3 other objectives, and in fact all the bits and pieces that make up a scope.

The stand has a built-in focussing block, smooth as silk and practically identical to my Olympus BHM block. 1 rotation of the fine adjustment gives 0.2mm advance; 1 division between tick marks =0.002mm advance. I suppose nimble fingers could move the fine adjustment so as to give 0.001mm advance. In fact, I just tried to do it with the aid of a magnifying glass and was successful.

Fine adjustment travels the entire distance of 20mm.

_________________NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Joined: 07 Nov 2006Posts: 1533Location: Germany, in the United States of Europe

Posted: Mon Feb 02, 2009 12:54 pm Post subject:

I´ve just checked:
If I am careful, I am able to get 10 movements between two "tick" marks of the Proxxon KT70 table.
(But, compared to some of you guys, I might be a bit less heavy-handed, so to speak! )

--Betty

Here aboard I've learned that in such cases it is appropriate to say:
[and now imagine me grumbling in a lowered false male voice]
"For what it's worth!"
Or:
"My five cents!"

edit: two tick marks (not to).

Last edited by Planapo on Mon Feb 02, 2009 3:12 pm; edited 1 time in total

I´ve just checked:
If I am careful, I am able to get 10 movements between to "tick" marks of the Proxxon KT70 table.
(But, compared to some of you guys, I might be a bit less heavy-handed, so to speak! )

Wow; just think what you could do with the Swift or Meiji block.

FWIW_________________NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Well, exposing all the gory details... To get 0.005 mm movement on my 10 turns-per-inch table, I have to use both hands and a lot of counter-torque to reduce the compliance of my sloppy human appendages. It's a trick I learned long ago for working with lathes and milling machines -- works fine, but like I say, it's a bit fidgety.